Contactless centrifugal pump

ABSTRACT

A centrifugal pump for use with a liquid is disclosed. The pump includes a hollow casing arrangement, a rotor and a magnet arrangement. The casing arrangement defines an interior and an intersecting axis, an intake port for receiving said liquid in use and communicating same to said interior and a discharge port communicating with the interior. The rotor is positioned in said interior and rotatable about said axis in spaced relation to said casing. The rotor includes a drive member, a shaft extending axially from the drive member and an impeller coupled to said drive member by said shaft for rotation therewith and adapted to cause fluid from said interior to be ejected through said discharge port upon rotation. The magnet arrangement is disposed outside said interior and is adapted to drive rotation of said drive member about said axis in use through the creation of a rotating magnetic field.

FIELD OF THE INVENTION

This invention relates to the field of centrifugal pumps and inparticular to a frictionless or contactless centrifugal pump.

BACKGROUND OF THE INVENTION

Contactless centrifugal pumps are known in the prior art.

One known type of contactless centrifugal pump has a one-piece rotor andimpeller including several permanent magnets inside the rotor. About theouter circumference of the casing that surrounds the impeller are twolayers (top and bottom) of electromagnets, and a corresponding number ofgap detection sensors. The upper layer of electromagnets uses the sensorsignals to adjust the repulsion and attraction force of eachelectromagnet, to set the gap between the rotating rotor and the casing,as well as the vertical position. The lower layer of electromagnets ispowered by an alternating current, causing the rotor to rotate. Theseare driven by a driver, which contains a micro CPU. In the course ofstopping, as the rotor decelerates it can be attracted to and touch theelectromagnet's core, causing wear. Additionally, this pump isstructurally complex, making maintenance relatively difficult forpersons other than specialists. Moreover, only relatively small capacitypumps (under 1 KW) of this type are typically made, and this type ofpump is relatively expensive when compared to other pumps.

Another known type of contactless centrifugal pump is described inJapanese Patent Publication No. 2005-090478, which is illustrated inFIG. 19 of this disclosure. In this pump, the impeller 40 is directlyconnected to a metal torque cylinder 41, and is able to rotate within a“can” structure 35. By rotating the magnets on the inside and outside ofthe can with a motor 37, rotational force is generated in the torquecylinder, which causes rotation thereof. As the impeller is free, andthe casing outflow 32 is towards the top of the structure, the liquidpressure within the casing 30 is such that P1<P2. Accordingly, theimpeller will float upwards and the center of the impeller O2 can becomehigher than the center of the casing O1. In order to keep the differencebetween P1 and P2 at a minimum, the inner wall 31 is attached to thecasing. However, when adjusting flow volume and discharge head, keepingP1 and P2 balanced is difficult. As the impeller rises, the torquecylinder can become caught on the can structure 35. As the impellertilts, the impeller touches the casing at points Q1 and Q2, and the canand torque cylinder touch at points Q3 through Q6. On the inner surfaceof the casing, wedge devices 33,34 are attached, however when theimpeller is tilted, their repulsive force is sharply decreased. (40-L,41-L) show the position of the impeller and torque cylinder when theyare tilted. Moreover, since the torque cylinder is cylindrical in shape,the magnets 36 must be attached to a cylindrical yoke, placing limits onboth the number and size of magnets and the radius of effect (RD) to theimpeller. Therefore the impeller output is constrained. Also, since thedischarge mouth is directly connected to the inner surface of the can,the discharge pressure is equal to the internal pressure. Since the canhas electromagnetic material property and thickness constraints placedon it, and pressure resistance constraints thereon, ultimately there aredischarge head constraints.

SUMMARY OF THE INVENTION

A centrifugal pump for use with a liquid forms one aspect of theinvention. This pump comprises a hollow casing arrangement, a rotor anda magnet arrangement. The hollow casing arrangement defines an interior,an axis intersecting the interior, an intake port for receiving saidliquid in use and communicating same to said interior and a dischargeport communicating with the interior. The rotor is positioned in saidinterior and is rotatable about said axis in spaced relation to saidhollow casing arrangement. The rotor includes a drive member; a shaftextending axially from the drive member; and an impeller coupled to saiddrive member by said shaft for rotation therewith and adapted to causefluid from said interior to be ejected through said discharge port uponsaid rotation. The magnet arrangement is disposed outside said interiorand is adapted to drive rotation of said drive member about said axis inuse through the creation of a rotating magnetic field.

A centrifugal pump for use with a liquid and a motor forms anotheraspect of the invention. The pump comprises a hollow casing arrangement,a rotor and a magnet arrangement. The hollow casing arrangement definesan interior, an axis intersecting the interior, an intake port forreceiving said liquid in use and communicating same to said interior anda discharge port communicating with the interior. The rotor ispositioned in said interior and is rotatable about said axis in spacedrelation to said hollow casing arrangement. The rotor includes animpeller adapted to cause fluid from said interior to be ejected throughsaid discharge port upon said rotation. The magnet arrangement isdisposed outside said interior, is coupled to said motor in use and isadapted to drive rotation of said rotor about said axis in use throughthe creation of a rotating magnetic field. The rotor and casingarrangement are adapted such that, in use, said liquid supports saidrotor for rotation substantially about said axis in spaced relation tosaid hollow casing arrangement.

According to other aspects of the invention, the impeller may be aclosed impeller. As well, the hollow casing arrangement may include: acentral casing defining a hole through which the shaft extends; a frontcasing defining, in combination with the central casing, a portion ofthe interior in which the impeller is positioned; and a rear casingdefining, in combination with the central casing, a portion of theinterior in which the drive member is positioned. Additionally, in use,the intake port may be horizontally disposed relative to said impellerand the discharge port may be upwardly disposed relative to saidimpeller.

According to another aspect of the invention, the rotor and casingarrangement may be shaped such that: a first portion of the spacebetween the rotor and the casing arrangement, in use, measured radially,undulates in magnitude around the impeller for stabilizing the rotoragainst radial movement; and a second portion of the space between therotor and the casing arrangement, in use, measured axially, undulates inmagnitude around the impeller for stabilizing the rotor against axialmovement.

According to other aspects of the invention, measured radially, in thedirection of rotation of the rotor, in each undulation in the firstportion the space between the rotor and the casing arrangement maygradually decrease and then quickly increase. As well, measured axially,in the direction of rotation of the rotor, in each undulation of thesecond portion the space between the rotor and the casing arrangementmay gradually decrease and then quickly increase.

According to other aspects, the impeller may have projecting fromaxially opposite sides thereof a pair of circular flanges, arrangedcoaxial with the axis; the casing may have defined therein a pair ofcircular channels in which the flanges rotate; the channels may havedefined therein a plurality of first wedge-shaped protuberances; and thespaces between the flanges, channels and first wedge-shapedprotuberances may define the first portion.

According to another aspect of the invention, the first wedge-shapedprotuberances may be circumferentially spaced-apart from one another anddisposed radially outwardly from the flanges.

According to another aspect of the invention, the casing arrangement mayhave defined thereon, on axially opposite sides of and in spacedrelation to the impeller, a plurality of second wedge-shapedprotuberances; and the spaces between the impeller and the secondwedge-shaped protuberances may define the second portion.

According to another aspect, the second wedge-shaped protuberances maybe formed on a pair of annular inserts fitted in hollows formed,respectively, on the front and central casing.

According to another aspect of the invention, the rotor and casingarrangement may be shaped such that a third portion of the space betweenthe rotor and the casing arrangement, in use, measured radially,undulates in magnitude around the drive member for stabilizing the rotoragainst radial movement.

According to another aspect of the invention, measured radially, in thedirection of rotation of the rotor, in each undulation of the thirdportion the space between the rotor and the casing arrangement maygradually decrease and then quickly increase.

According to another aspect of the invention, the drive member may haveprojecting in an axial direction therefrom a circular flange, arrangedcoaxial with the axis; the casing arrangement may have defined therein acircular channel in which the flange rotates in use; the channel mayhave defined therein a plurality of first wedge-shaped protuberances;and the space between the flange, channel and first wedge-shapedprotuberances may define the third portion.

According to another aspect of the invention, the first wedge-shapedprotuberances may be circumferentially spaced-apart from one another anddisposed radially outwardly from the flange projecting from the drivemember.

According to another aspect of the invention, said adaptation of therotor and casing arrangement, such that said liquid supports said rotorin use for rotation substantially about said axis in spaced relation tosaid hollow casing arrangement, may comprise: a first wedge device whicharrests radial translation of the rotor in use; and a second wedgedevice which arrests axial translation of the rotor in use.

According to another aspect of the invention, the pump may furthercomprise a first wedge device which arrests radial translation of therotor in use; and a second wedge device which arrests axial translationof the rotor in use.

According to other aspects of the invention, the shaft may havepositioned thereon at least one wing for arresting liquid flow from theimpeller towards the drive member in use.

According to another aspect of the invention, at least one wing may be aa spiral wing.

According to another aspect of the invention, the pump may furthercomprise a conduit providing for fluid communication between a portionof the interior in which the drive member is positioned and the intakeport.

According to another aspect, the drive member may comprise: a rotorplate having a rim; and a non-magnetic electrical conductor secured tosaid rim, the conductor having a surface coated in an insulator. Aswell, the casing arrangement may include a non-magnetic electricalinsulating barrier between the conductor and the magnet arrangement, andthe magnet arrangement may comprise two sets of permanent magnetssurrounding said conductor and rotatable in use such that, upon saidrotation, said rotating magnetic field is generated between the two setsof magnets to intersect the conductor.

According to another aspect of the invention, the conductor may be anannular disc and each of the two sets of permanent magnets may includean even number of permanent magnets arranged in an arc and attached to ayoke, the yokes of the two sets being connected together and the twosets of permanent magnets being axially spaced from one another.

According to another aspect of the invention, the conductor may be ahollow cylinder and each of the two sets of permanent magnets mayinclude an even number of permanent magnets arranged in an arc andattached to a cylindrical yoke, the yokes of the two sets beingconnected together and the two sets of permanent magnets being radiallyspaced from one another.

The combination of the motor with a centrifugal pump, with the motorbeing coupled to the magnet arrangement and, in use, driving said magnetarrangement to create said rotating magnetic field, forms yet anotheraspect of the invention.

Notably, in these centrifugal pumps, the impeller and connected partsrotate substantially entirely without rubbing against the adjacentstructures, and have no seals or immersed bearings. Other advantages,features and characteristics of the present invention, as well asmethods of operation and functions of the related elements of thestructure, and the combination of parts and economies of manufacture,will become more apparent upon consideration of the following detaileddescription and the appended claims with reference to the accompanyingdrawings, the latter being briefly described hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of a pump constructed according to afirst preferred embodiment of the invention with torque device 1installed;

FIG. 2 is a diagram of a dual layer wall of the front casing

FIG. 3 is a plane figure operational diagram of Wedge Device 2

FIG. 4 is an X1-Y1 cross-sectional diagram of FIG. 3

FIG. 5 is a cross-sectional Diagram of Wedge Device 1

FIG. 6 is an X2-Y2 cross-sectional diagram of FIG. 5

FIG. 7 is a diagram of Wedge Device

FIG. 8 is a diagram showing range of the wedge effect with the use ofwedges

FIG. 9 is a diagram showing range of the wedge effect without the use ofwedges

FIG. 10 is an external side view diagram of Torque Device I

FIG. 11 is an X3-Y3 direction plane diagram of FIG. 10

FIG. 12 is an X4-Y4 direction plane diagram of FIG. 10

FIG. 13 is a diagram showing the relationship between the rotor plate,torque disc, primary and secondary magnets

FIG. 14 is an X5-Y5 direction plane diagram of FIG. 13

FIG. 15 is a cross-sectional diagram of a pump constructed according toa second preferred embodiment of the present invention, with TorqueDevice II installed

FIG. 16 is an external side view diagram of Torque Device II

FIG. 17 is an X6-Y6 direction plane diagram of FIG. 16

FIG. 18 is a curve showing the relationship between Torque, RepulsiveForce, Wedge Effect, Slip

FIG. 19 is a skeleton diagram of a prior art pump

DESCRIPTION OF THE INVENTION

FIG. 1 and FIG. 15 are cross-section diagrams of pumps constructedaccording to a first preferred embodiment and a second preferredembodiment, respectively, of the invention. The pumps are generallysimilar in structure and operation to one another, but for the form of atorque generation device/drive member employed therein. FIGS. 1, 15 showthe pumps with Torque Generation Device I (104) and Torque GenerationDevice II (104′)) installed, respectively, which Devices I, II are fullydescribed hereinafter.

Generally, each pump is comprised of three casings, namely, front casing(1), central casing (2) and rear casing (3), which are connectedtogether to form a hollow casing arrangement having an interiordesignated with general reference numeral 100. The interior has an axisA-A. Within a portion 110 of the interior 100, the impeller (6) ispositioned. The front casing contains an inner wall (1-1) which has adouble layer construction. It also contains the inflow mouth or intakeport (4) and discharge mouth or port (5). Attached between the sides ofthe front casing (1) and impeller (6) and the central casing (2), areWedge Devices 1 (8,9) and Wedge Devices 2 (11,12). The front (1),central (2) and rear (3) casings, with the impeller (6), form the mainbody of the pump, and regardless of whether Torque Generation Device Ior II are installed, the construction of this main body is the same inthese preferred embodiments.

In a portion 112 of the interior 100 between the central casing (2) andrear casing (3) is positioned a resin disc (hereafter referred to as therotor plate) that forms the core (A20 or B20) of each of TorqueGeneration Devices I, II. Passing through the center of the centralcasing (2) is a throughhole 108 through which passes a connective shaft(7) that connects the impeller (6) to the rotor plate (A20 or B20). Theimpeller (6), shaft (7) and Torque Generation Device I or II togetherdefine a rotor (1102). This connective shaft (7) has neither bearingsnor a seal device. Attached to the connective shaft (7) are severalsmall spiral wings (15) which serve to prevent or arrest the flow ofliquid along the throughhole 108. Attached to the rotor plate and thecorresponding casing face, is a further Wedge Device 1 (10). Also, inorder to obtain balanced internal pressure, a tube (16) (hereafterreferred to as the pressure equalization tube) connects the interior ofthe pump proximal to the Torque Generation Device to the inflow mouth(4).

The Torque Generation Device is a device that generates the impellerdriving power, the construction of which is described as follows.Attached to the rotor plate (A20,B20) are either torque disc (A-21) or atorque cylinder (B-21), which are isolated by a non-magnetic electricalinsulating can (A3-C, A2-C). By rotating a series of permanent magnetson the outside of the can, a rotating magnetic field is generated whichintersects the torque disc (A-21) or torque cylinder (B-21). The torquedisc (A-21) or torque cylinder (B-21) is made from a non-magneticelectrical conductor, the surface of which is insulated. The group ofmagnets form part of a magnet arrangement 106 and are synchronouslyrotated by a motor (29) to create a rotating magnetic field. Also, therotating parts of the magnets are covered by a cover.

The effects achievable by this invention will be described below. Theinner wall (1-1) is attached inside the impeller casing, and theimpeller (6) is arranged within the inner wall (1-1). Placedsymmetrically within inner wall (1-1) are discharge holes (1-1-1,1-1-2). The upward discharge holes (1-1-1) are shifted slightly frombeing directly under the casing discharge mouth (5). While this preventsthe vertical direction liquid pressure from being completely equal, itdoes lessen the overall difference. Furthermore, the wobble of theimpeller (6) is minimized, allowing it to rotate roughly in the centerof the can (A3-C, A2-C, B3-C), preventing rubbing against the inner wall(1-1). Attached to both sides of the impeller (6) plate, and one side ofthe rotor plate (A20) are some cylindrical protrusions or flanges (6-1).Defined into the corresponding inside of the casing are annular channels(1-3) into which these protrusions are fitted. A plurality of firstwedge-shaped protrusions (8-1) are defined on or secured to the surfaceof the channels, radially outwardly from the flange. Each flange (6-1),along with the channel in which it is positioned, and the firstwedge-shaped protuberances (8-1) projecting into said channel, define arespective Wedge Device 1 (8,9,10). With these Wedge Devices 1, arepulsive force is generated whenever the impeller (6) or rotor plate(A20,B20) approach the top or bottom faces of the surrounding wall, andthis prevents both the impeller (6) and rotor plate (A20) from rubbingagainst the surrounding wall in the vertical direction. That is, WedgeDevices 1 serve to minimize radial movement or translation of the rotor(i.e. movement that is not parallel to the axis A-A). A Wedge Device 2is provided for each face of the impeller (6). Wedge Device 2 takes theform of an annular insert plate (11,12) fitted in a matching hollowdefined in the casing surfaces facing the impeller faces. These WedgeDevices 2 are provided with a plurality of second wedge-shapedprotrusions (8-2). These Wedge Devices 2 generate a repulsive forcewhenever the impeller (6) approaches the casing in the horizontal oraxial direction, i.e. parallel to axis A-A, preventing the impeller (6)from rubbing against the casing from the left and right.

The details of each part of an actual realization of the pump, areexplained in the figures described below. Those parts in the drawingsthat are labeled with an A (e.g. A20) are related parts to TorqueGeneration Device I, whereas those that are labeled with a B (e.g. B20)are related to Torque Generation Device II. FIG. 2 shows the frontcasing (1), its inner wall (1-1) and the casing internal pressure. Theimpeller (6) is within the inner wall, and the liquid passage (1-2) isbetween the casing (1) and the inner wall (1-1). The liquid passage isconnected to the discharge mouth (5). Within the inner wall (1-1) aresymmetrically placed discharge holes (1-1-1, 1-1-2), placed such thatthey are not directly underneath the discharge mouth (5). This makes thedifference between P1 and P2 smaller, and protects against unnecessarycore wobble of the impeller. With respect to the position of thedischarge mouth (5), the liquid pressure within the inner wall and theimpeller are such that P1<P2, and making P1=P2 is exceedingly difficult.When P1<P2, the center of the impeller (O 2) will wobble from the casingcenter (O 1) towards the lower pressure P1 side, making it possible forthe impeller (6) to rub up against the inner wall (1-1). When theimpeller (6) is stopped, it falls, touching the inner wall on its bottomside, but when it starts to rotate, it simultaneously lifts up from theinner wall. While in operation, in order to for the impeller (6) not totouch the surrounding walls, it is necessary for the impeller to rotatein the center of the casing as much as possible without wobbling. Inorder to minimize the wobble, Wedge Devices 1 and Wedge Devices 2, areprovided. In other words, it is desirable that O 1 and O 2 are roughlyaligned during operation.

FIG. 3 is a plane figure diagram of Wedge Device 2 (11), of which FIG. 4is a X1-Y1 cross-section. This wedge device comprises an insert (11)attached to the inner wall of the casing, and interacts with rotatingparts (e.g. the side of the impeller) such that it prevents contact ofthe impeller with the casing. If there is no liquid or liquid flowbetween the wedge surface (11-1) and the side of the impeller (6) therewill be no wedge effect, therefore an appropriate space, in the form ofa liquid entry guide (11-2) has been left out. In the event that theimpeller (6) is tilted (6-L), the wedge effect will decreasedramatically. The second wedge-shaped protrusions (8-2) on the insert(11) are such that, measured axially, a second portion (116) of thespace (118) between the rotor and the casing arrangement undulates inmagnitude around the impeller; more specifically, in the direction ofrotation of the rotor, it repeatedly gradually decreases and thenquickly increases.

FIG. 5 is a cross-sectional diagram of the Wedge Device 1 (8) that is inbetween the impeller (6) and the front casing (1). FIG. 6 is an X2-Y2cross-sectional diagram of FIG. 5. Within the cylindrical opening orchannel (1-3) in the front casing (1), a cylindrical protuberance orflange (6-1) on the impeller (6) is inserted. About the outercircumference of the inner face of the hole or channel (1-3), severalfirst wedge-shaped protuberances (8-1) are attached or formed. The firstwedge-shaped protrusions (8-1) are such that, measured radially, a firstportion 114 of the space between the rotor and the casing arrangementundulates in magnitude around the impeller, more specifically, in thedirection of rotation of the rotor, it repeatedly gradually decreasesand then quickly increases. The flange (6-1), channel (1-3) andprotuberances (8-1) together define Wedge Device 1 (8), which serves toprevent the rotating parts (6-1) from contacting with the top and bottomfaces of the casing. When the rotating parts are stopped, they touch thebottom face, but when starting to rotate, they simultaneously separate.

FIG. 7 is an explanatory diagram of the basic operation of the wedgeeffect provided by Wedge Devices 1,2. In between the stationary side(Z1) and the rotary side (Z2) there is a narrow gap (h₁). Liquid in h₁rotates due to the rotation of the rotary side. The wedge pieces (WG)are attached to the stationary side, with length α, width β, inclinationθ, liquid viscosity μ. The number of wedge pieces is designated as n.

While the rotary side (Z2) rotates, it variously approaches andseparates from the stationary side. In other words, the space betweenthe rotary side and stationary side undulates in magnitude, in eachundulation, gradually decreasing and then quickly increasing. If onedesignates the largest separation gap between the rotary side and thewedges as (h₂) and the smallest separation gap as (h₀). then the forceof the wedge effect (F), or in other words, the force that resists thefurther approach of the rotary side, is explained briefly below:Effect Force: F)=K·μ·ν·α·β² ·n·1/h ₀ ²where K is the proportionality constant, μ the liquid viscosity, ν isthe speed of rotation, α is the length of the wedge face, β is the widthof the wedge face, h₀ is the smallest gap size, and n the number ofwedge faces.

Accordingly, as Z2 approaches, h₀ becomes smaller, and the repulsiveforce becomes geometrically larger. The angle of inclination θ affectsboth the point of maximum wedge effect power on the wedge face as wellas the overall repelling power. Regarding the illustrated device,θ=2-4°, h₀=0.1-0.3 mm has been set as a standard. Also, it has beenempirically verified that when the surfaces Z1 and Z2 are not parallel,and rather inclined to one another, the wedge effect decreasesdramatically. Also, if the corresponding face on Wedge Device 2 is aplane surface, and inclined wedges are not attached, there will be nowedge effect. As the rotary side (Z2) is free, when it stops, it touchesthe stationary side (Z2) to the bottom of it. At that time, h₀=0. Whenthe pump is switched on, the pressure buildup due to the flow of liquidreaches it's maximum, pushing up Z2 and h₀<>0. In other words, Z2separates from Z1. That this phenomenon occurs simultaneously when thepump is switched on confirms that Z1 and Z2 do not rub against oneanother.

FIGS. 8 and 9 show that if both the stationary and rotary sides arecylindrical, even if there are no wedges placed on both sides of thegap, then to some degree the wedge effect will appear when the gapchanges, but if the wedges are attached, the effect is larger. FIG. 8considers the situation with wedges, and FIG. 9 considers the situationwithout wedges. The bounding limit for the wedge effect is such thatα1>>α2.

FIG. 1 and FIG. 15 show the connective shaft (7), which passes throughthe hole (108) in the center of the central casing (2), connecting therotor plate (A20, B20) to the impeller (6). Attached to this shaft are anumber of small spiral wings (15). During operation, some of the liquidthat heads towards the discharge mouth (5) because of the rotation ofthe impeller (6), passes through this hole and enters the gap (G)between the rotor plate and central casing (2), and the rear casing (3)and rotor plate (A20 or B20). When this happens, the rotation of shaftwings (15) protects against the liquid influx into this gap, and alsoprotects against rising liquid pressure inside this gap. However, sincethe liquid pressure in this gap does rise gradually, a tube (16) isattached which connects the gap to the low liquid pressure inflow mouth(4), thus protecting against rising liquid pressure within the gap.Furthermore, when (16-1) goes above a set pressure, it opens and acts asrelief valve. By doing this, one can be fairly confident that the gap orcan (A2-C, A3-C and B3-C) internal pressure is maintained at a constantlevel, without any relation to the impeller discharge pressure, in otherwords, the change in discharge head, thus making it possible to dealwith changing the discharge head. In other words, it is possible to alsohave a high discharge head. The can is made of a non-magnetic electricalinsulating material and to be strong enough to withstand moderatepressures. There are times when residual air builds up within the gap.When this residual air becomes too much, there is a possibility that itmight flow into the impeller and cause harm, so a valve (16-2) isprovided to discharge it at that time. Traditional construction, whichconnects the impeller directly to the torque generating part, fails toproduce the above effects, and is only achievable by the disconnectedconstruction used in this invention.

Next, Torque Generation Device I will be described as shown in FIGS. 1,10, 11, 12, 13, and 14. In front of the code for each part which isrelated to Torque Generation Device I is the letter A. For example, A20,A21 etc. The right side of FIG. 1 is a longitudinal cross section of thewhole device. As seen in FIG. 1, a Wedge Device 1 (10) is provided onthe rotor plate (A20) and the corresponding face of the central casing(2). The space between the first wedge-shaped protrusions and flange ofWedge Device 1 (10) define a third portion (120) of the space betweenthe rotor and casing arrangement which, measured radially, undulates inmagnitude about the drive member. Attached to the rim of the rotor plate(A20) is the annulus of the Torque Generating Disc (hereafter referredto as the Torque Disc (A-21)). Torque Disc (A-21) is an annulated discmade of a non-magnetic electrical conductor of appropriate thickness andwidth, the surface of which is covered in an insulating resin (A21-1).FIG. 10 is an external side view drawing of Torque Generation Device I.

FIG. 11 is an overhead X3-Y3 plane view of FIG. 10, and a plane diagramof the primary magnets (A22) as installed into the yoke plate (A24). Themagnets (A22) are placed in an arc, in an even number, such that thesurface of the adjacent magnet will have opposite polarity, and theywill alternate in polarity throughout. The yoke plate (A24) is made outof a magnetic material (e.g. a metal plate) of appropriate thickness,such that a sufficient amount of magnetic flux from each magnet willpass through the plate completely. The primary yoke plate (A24) isconnected to the secondary magnet's yoke plate (A25) at the cylindricalpart (A25-2) by bolts (A26) at several places. The separation distancebetween each magnet is designated as g₁. As for the magnetic materialused in this device, Neodymium magnets (NF-40/45) are used as thestandard. The size of the magnetic gap (g₀), and the thickness of themagnet (WD) are chosen to satisfy the following condition: that themagnetic flux between primary and secondary effectively intersectthrough the Torque Disc (A21). In other words, they are arranged tominimize leakage flux, and g₀<g₁, g₀<WD.

FIG. 12 is an overhead X4-Y4 plane drawing of FIG. 10, and a planedrawing of the secondary magnets (A23) as installed in the yoke plate(A25). The yoke plate (A25) is of a magnetic material, and the part intowhich the magnets are attached is a disc (A25-1). The part whichconnects it to the primary magnet's yoke plate (A24) is in the form of acylinder (A25-2). For the ease of assembly and disassembly, this yoke(A25) can be split from top to bottom into two pieces; (A25-3) shows thesplit. The material and arrangement shape of the secondary magnets arecompletely identical, and the installation arrangement is symmetrical tothat of the primary magnets. That is to say, the polarity of the primarymagnet is the opposite to that of the corresponding secondary magnet.

FIG. 13 shows the arrangement relationship of the primary magnets (A22)the secondary magnets (A23) and the torque generation disc (A21). FIG.14 is a X5-Y5 overhead view of FIG. 13, showing the torque plate (A21)which is attached to the rotor plate (A20) and its insulating plate(A21-1). The torque disc (A21) is an annulated disc of appropriatethickness to generate an effective amount of torque, and is made of anon-magnetic electrical conductor (Cu, Al etc.). This is attached to therim of the rotor plate, and one of its sides is covered in a resin plate(A21-1). These parts are all glued together. The rotor plate coatingdoes not use thermal spray resin coating since insulating plates made ofa thermal spray coating have a limit on their processing thickness, andalso are porous, such that there is a danger of liquid permeating as faras the torque disc. The primary and secondary magnets sandwich the can(A2-C, A3-C), which in turn sandwiches the torque disc, allowing forsynchronous rotation. If at the torque disc thickness is designated t0,the thickness of both sides of the insulating material designated as t1,the can (A2-C,A3-C) thickness t2, the distance between the primary andsecondary magnets as g₀, the gap between the can (A2-C, A3-C) and thetorque disc as g₂, and the gap between the can and the primary andsecondary magnets each as g₃, then the distance between the primary andsecondary magnets, or the magnetic gap becomes: g₀=t0+2t1+2t2+2g₂+2g₃.Within this invention if to is 3-4 mm, t1 is 1.5-2 mm, t2 is 3-4 mm, g₃is 0.5-1 mm, g₂ is 0.5-1 mm, then g₀ is approximately 20 mm. FIG. 14 isa an X5-Y5 plane diagram of FIG. 13 that shows the relationship betweenthe rotor plate (A20) the attached torque disc (A21) the torque discinsulator (A21-1) and the torque effective radius of operation of thetorque disc.

Next, Torque Generation Device II will be described as shown in FIGS.15, 16, and 17. In front of the code for each part which is related toTorque Generation Device II is the letter B. For example, B20, B21 etc.FIG. 15 is a cross-sectional drawing of the whole device. The main bodyof the pump is the same as in FIG. 1. and a separate drawing istherefore omitted. The right side of FIG. 15 is a longitudinal crosssection of the Torque Generation Device II. Wedge Device 1 (10) isattached to the rotor plate (A20) and the corresponding face of thecentral casing (2). Attached perpendicularly to the rim of the rotorplate is the Torque Cylinder (B21). The Torque Cylinder is a cylinder ofappropriate length and thickness, made of a non-magnetic electricalconductor, the surface of which is covered in an insulating resin.

FIG. 16 is an external view of Torque Generation Device II, and FIG. 17is an X6-Y6 cross-sectional diagram of FIG. 16. The torque cylinder(B-21) is separated from the 2 layer cylinder can (B3-C) by a gap (g₂).The can is connected at both ends with the central casing (2) and therear casing (3). The can is made of a non-magnetic electrical insulator.

The torque cylinder is sandwiched by the can, which in turn issandwiched by two set of magnets. On the outside, the primary magnets(B22) are installed, on the inside, the secondary magnets (B23) areinstalled. The outside and inside magnets are each attached to theirrespective cylindrical magnetic yokes (B25-1, B25-2). The size of boththe inside and outside magnets are roughly the same, and are provided inthe same even number. The corresponding inside and outside magnets haveopposite polarities to one another. As well, each adjacent magnet alsohas the opposite polarity. If the distance between the inside andoutside magnets, (i.e. the magnetic gap), is designated g₀, the distancebetween each adjacent magnet (g₁), the effective width of the magnets(WB), the thickness (WD), then the conditions g₀<g₁, g₀<WD are the sameas with Torque Device I. The inside and outside magnets are attached tothe yoke cylinder (B25-2) outer surface and B25-1's inner surfacerespectively. (B25-1) and (B25-2) are attached together by bolts (B26)to the yoke disc (B24), and are synchronously rotated by a driving motor(29). In this device as well g₀ is roughly 20 mm, and the standardmagnets used are NF-40. When compared to ordinary general purpose pumps,the value for g₀ is quite large, around 20 mm in Torque Device I and II.When g₀ is large, and trying to generate a rotating magnetic field in g₀with a wrapped coil device, excitation losses are especially large, andthere is heat generated. Also, it becomes difficult to use this pump forexplosion prevention applications. For the reasons above, this inventionuses a design of generating a magnetic field by rotating a series ofpermanent magnets, and by this design it is expected that there will bea benefit of preventing the above inefficiencies.

The torque (T₀) generated by one pair of magnets in the torque disc ortorque cylinder is as follows: $\begin{matrix}{T_{o} = {{K_{1} \cdot \theta \cdot I}\quad{\alpha \cdot R}}} \\{= {K_{1} \cdot \theta \cdot {e/{\rho\gamma}} \cdot R}} \\{= {{K_{1} \cdot \theta \cdot K_{2}}\theta\quad n_{o}{{S/{\rho\gamma}} \cdot R}}}\end{matrix}$The torque imparted on the impeller is:T=K·θ ² ·n _(o) ·S·1/ρÖγ·R·NP

The primary and secondary magnets, and the inner and outside magnets aretreated as the primary and secondary magnets, and the torque disc andtorque cylinder are treated as the torque disc. K, K₁, K₂proportionality constant Θ magnetic flux density between primary andsecondary magnets that induces e e the voltage induced in the torquedisc or inside the torque cylinder by change in phi ργ electricresistance of the torque disc or torque cylinder (dependent on thicknessand material) n_(o) rpm of the magnets (identical to motor rpm) n rpm ofthe torque disc S (S = n_(o) − n/n_(o)) the slippage with respect ton_(o) by the torque disc or torque cylinder R radius of effect (RA orRB) NP the number of pairs of the primary and secondary magnet I eddycurrent according to the Fleming RuleAlso, phi's magnitude is inversely proportional to g₀, proportional toWB, and nearly unrelated to WL. According the above equation, in orderincrease the torque T, and the pump's discharge power, it is necessaryto make the number of pairs of attached magnets and the radius of effect(RA or RB) structurally large. In this respect, comparing this inventionto earlier devices (see FIG. 19) RA or RB are larger than RD, and thereare a greater number of pairs of attached magnets, this invention isable to have a greater capacity.

FIG. 18 is a diagram that shows the properties of, the repulsive forcedue to Wedge Device I (FA), the electromagnetic repulsion (Fm), Torque(T), and the slip (S) while the pump is operating, between the rpm ofthe torque disc or torque cylinder and the rpm of the magnets. Thetorque T is the same for Torque Generation Device I and II, but theElectromagnetic repulsion (Fm) has a different direction from TorqueDevice I to II, and the repulsive force from Wedge Device 1 (FA) is thesame for both Torque Generation Devices. The Electromagnetic repulsion(Fm) is a cross product of the magnetic Reynolds number (Rm) and theslip, and appears between the magnets and the torque disc or torquecylinder when S*Rm>1. In other words, with Torque Device I it appearslaterally between the torque disc and the magnets, and with TorqueDevice II, it appears vertically between the torque cylinder and themagnets. Here, the magnetic Reynolds number (Rm) is a value that comesfrom the electromagnetic configuration, speed of the rotating parts, andthe slip, the electromagnetic repulsion is at its maximum duringactivation. When stopped, Wedge Device I has h₀=0, and the rotatingparts, are touching the bottom of the casing, but when starting therepulsive force due to the flow of liquid is at its greatest, such thatthe rotating parts separate from the casing. The combined force of Fmand FA is shown in the Fm+FA curve. Also, if a brake is added to thedriving motor, when decelerating to an appropriate speed, the brake isengaged, then stopping will be gradual and smooth, and no rubbing willoccur.

The disassembly and assembly of the pump when Torque Device I isinstalled is described hereinafter with reference to FIG. 1. As a firststep, by releasing connecting bolts (13,14) and the impeller restrainingscrew (7-1), the front casing (1) and the impeller (6) can be removed.Release of bolt (27-1), and removal the cover (27), can be followed byremoving bolt (A26) and the secondary magnet yoke split bolts (A25-4).The secondary magnets and the yoke part can then be removed. Finally, byremoving the can restraining screws (A3-C-1), the central casing (2),connective shaft (7), rotor plate (A20) and rear casing (3) can beremoved. In assembly, the above steps can be followed in reverse.

With regard to the matter of the disassembly and assembly of the pumpwhen Torque Device II is installed, a first step is the removal ofconnecting bolts (13,14) and the impeller restraining screw (7-1).Thereafter, all the parts can be disassembled. For the purpose ofassembly, the above steps can be followed in reverse. In comparison tothe first preferred embodiment of the pump, assembly and disassembly ofthe second preferred embodiment of the pump is extremely simple, andwhen there exists a need for frequent cleaning and internal inspection,the second preferred embodiment is an advantageous selection.

The centrifugal pumps described herein can handle pure water, as well ascorrosive liquids (including acids, alkalis and electrolytic corrosiveliquid) without a problem, other uses include suction or removal of allvariety of liquids, such as fine slurry mixtures, etc. It can be used ina wide range of technical fields.

Specification of the test machine, and the test results are according toTable 1 below. Unless otherwise specified, parts in the table are allmade from ultra high density polyethylene. Units of measurement are inmm. TABLE 1 Torque Gen Torque Item Detail Device I GenDevice II Frontcasing Inflow Diameter * Outflow Diameter 65A * 40A 50A * 25A InternalDouble Layer Wall Yes Yes Impeller Outer Diameter * Inner DiameterΘ150 * θ60 Θ140 * θ50 No. Wings 6 5 Rotation Per Minute 3300 r.p.m. 3200r.p.m. Specific Speed 177 ns 137 ns Wedge Device 1 Number attached 3 3Wedge Device 2 Number attached 2 2 Connective Shaft Wings Quantity 8 8Rotor Plate Outside Diameter Θ200   Θ180   Torque Disc/Torque CylinderMaterial 99% Cu 99% Cu Outer Diameter/Inner Θ190/110/4 Θ175/167/(4)Diameter/Thickness (Width) Radius of effect (R) 93  85  Can Thickness 33 Attached Magnets Material (Neodymium Magnets) NF-40 NF-40 (attachmentyoke material, SS- No. Attached 10  8 400, thickness 10 mm) Magnetic Gap(g_(o)) ≈20  ≈20  Driving Motor (AC 220/200 V * Rated RPM 3420 r.p.m. *with Break 7.5 kW 5.5 kW 2 P * 60 Hz) Test Results (no empty runs)Discharge Head (m) 40  30  Flow Rate (L/min) ≈500   ≈400   TorqueDisc/Torque Cylinder slippage  ≈3.5%  ≈6% (%) Efficiency (%) 43  35 Rubbing Parts None None

PARTS LIST 1 Front Casing 1-1 Casing Inner Wall 1-1-1 Casing Inner WallDischarge Hole 1-1-2 Casing Inner Wall Discharge Hole 1-2 Liquid FlowPath 1-3 Cylindrical groove 2 Central casing 2-1 Support Plate A2-C Can(Partition) Portion 3 Rear Casing A3-C Can (Partition) Portion A3-C-1Can Restraining Screw B3-C Can 4 Inflow or intake port 5 Outflow(discharge mouth or port) 6 Impeller 6-1 Cylindrical protrusions orflanges 6-L Inclined impeller position 7 Connective shaft 7-1 ConnectingScrew 7-2 Connecting Screw 8 Wedge Device 1 8-1 First wedge-shapedprotrusion 8-2 Second wedge-shaped protrusion 8-g Wedge Gap 9 WedgeDevice 1 10 Wedge Device 1 11 Wedge Device 2 11-1 Wedge Surface 11-2Liquid entry guide 11-G Minimum Gap 12 Wedge Device 2 13 Connective Bolt14 Connective Bolt 15 Screw wings 16 Pressure equalization tube orconduit 16-1 Relief valve 16-2 Open-close valve A20 Rotor plate A21Torque disc A21-1 Cover plate A22 Primary Magnets A23 Secondary MagnetsA24 Primary Magnet Yoke A25 Secondary Magnet Yoke A25-1 Secondary MagnetYoke Plate A25-2 Secondary magnet yoke cylinder A25-3 Secondary MagnetYoke split A25-4 Yoke split connective bolt A26 A24-A25 connective boltsB3-C Can B20 Rotor Plate B21 Torque cylinder B22 Outer (Primary) MagnetsB23 Inner (Secondary) Magnets B24 Connective yoke plate B25-1 OuterMagnet Yoke Cylinder B25-2 Inner Magnet Yoke (Inner Yoke (Outer YokeCylinder) Cylinder) B26 B25-1, B25-2, B26, Connective G Gap betweenrotor plate, and Bolt central and rear casings 27 Protective cover 28Thrust bearing 29 Driving motor 30 Impeller casing 31 Inner wall 32Outflow (discharge mouth) 33 Wedge Device 2 34 Wedge Device 2 36 Inner,Outer Magnets 37 Driving Motor 40 Impeller 40-1 Inclined impellerposition 41 Torque cylinder 41-L Inclined Rotor position O1 Center ofthe casing O2 Center of the impeller P1 Pressure between the impellerand P2 Pressure between the impeller and inner wall at the top the innerwall at the bottom LQ Liquid in the wedge gap V Velocity of the movingside (rotational velocity) α Wedge Length β Wedge Width Θ WedgeInclination WG Wedge h₁ Maximum Wedge Gap h₀ Minimum Wedge Gap Z1Stationary Side Z2 Rotary size A1 Effective Range of the Wedge α2Effective Range of the Wedge Effect Effect WB Vertical Width of theMagnet (the WL Horizontal width of the magnet width that crosses thedirection of (the width that is concurrent with rotation of the torquedisc or the direction of rotation of the torque cylinder) torque disc ortorque cylinder) WD Thickness of the Magnet g_(o) Distance between theprimary and secondary magnets (magnetic gap) g₁ Distance between themagnets g₂ The gap between the can and the torque disc (A21) or torquecylinder (B21) g₃ The distance between the can and RA Radius of effectthe magnets RB Radius of Effect RD Radius of effect S slip T Torque FElectromagnetic attractive force Fm Electromagnetic repulsive force FARepulsive force due to the wedge S1 Slip during normal operation effectQ1 Contact points between impeller Q2 Contact points between impellerand casing and casing Q3-Q6 Contact points between the rotor 100Interior of casing assembly and the can A—A Axis of casing assembly 102Rotor 104, 104′ Drive member 106 Magnet arrangement 108 Hole throughcentral casing 110 Portion of interior surrounding impeller 112 Portionof interior surrounding 114 First portion of interior space drive member116 Second portion of interior space 118 Space between rotor and casing,generally 120 Third portion of interior space 35 Can structure

Finally, it is to be understood that while but two embodiments of thepresent invention have been herein shown and described, it will beunderstood that various changes in size and shape of parts may be made.It will be evident that these modifications, and others which may beobvious to persons of ordinary skill in the art, maybe made withoutdeparting from the spirit or scope of the invention, which isaccordingly limited only by the claims appended hereto, purposivelyconstrued.

1. A centrifugal pump for use with a liquid, said pump comprising: ahollow casing arrangement defining an interior, an axis intersecting theinterior, an intake port for receiving said liquid in use andcommunicating same to said interior and a discharge port communicatingwith the interior; a rotor positioned in said interior and rotatableabout said axis in spaced relation to said hollow casing arrangement,said rotor including: a drive member; a shaft extending axially from thedrive member; and an impeller coupled to said drive member by said shaftfor rotation therewith and adapted to cause fluid from said interior tobe ejected through said discharge port upon said rotation, and a magnetarrangement disposed outside said interior and adapted to drive rotationof said drive member about said axis in use through the creation of arotating magnetic field.
 2. A centrifugal pump for use with a liquid anda motor, said pump comprising: a hollow casing arrangement defining aninterior, an axis intersecting the interior, an intake port forreceiving said liquid in use and communicating same to said interior anda discharge port communicating with the interior; a rotor positioned insaid interior and rotatable about said axis in spaced relation to saidhollow casing arrangement, said rotor including an impeller adapted tocause fluid from said interior to be ejected through said discharge portupon said rotation; and a magnet arrangement disposed outside saidinterior, coupled to said motor in use and adapted to drive rotation ofsaid rotor about said axis in use through the creation of a rotatingmagnetic field, the rotor and casing arrangement being adapted suchthat, in use, said liquid supports said rotor for rotation substantiallyabout said axis in spaced relation to said hollow casing arrangement. 3.A centrifugal pump according to claim 1, wherein the impeller is aclosed impeller; the hollow casing arrangement includes a central casingdefining a hole through which the shaft extends a front casing defining,in combination with the central casing, a portion of the interior inwhich the impeller is positioned; and a rear casing defining, incombination with the central casing, a portion of the interior in whichthe drive member is positioned; and in use, the intake port ishorizontally disposed relative to said impeller and the discharge portis upwardly disposed relative to said impeller.
 4. A centrifugal pumpaccording to claim 2, wherein the rotor and casing arrangement areshaped such that a first portion of the space between the rotor and thecasing arrangement, in use, measured radially, undulates in magnitudearound the impeller for stabilizing the rotor against radial movement;and a second portion of the space between the rotor and the casingarrangement, in use, measured axially, undulates in magnitude around theimpeller for stabilizing the rotor against axial movement.
 5. Acentrifugal pump according to claim 4, wherein measured radially, in thedirection of rotation of the rotor, in each undulation in the firstportion the space between the rotor and the casing arrangement graduallydecreases and then quickly increases.
 6. A centrifugal pump according toclaim 5, wherein measured axially, in the direction of rotation of therotor, in each undulation in the second portion the space between therotor and the casing arrangement gradually decreases and then quicklyincreases.
 7. A centrifugal pump according to claim 6, wherein theimpeller has projecting from axially opposite sides thereof a pair ofcircular flanges, arranged coaxial with the axis; the casing arrangementhas defined therein a pair of circular channels in which the flangesrotate in use; the channels have defined therein a plurality of firstwedge-shaped protuberances; and the spaces between the flanges, channelsand first wedge-shaped protuberances define the first portion.
 8. Acentrifugal pump according to claim 7, wherein the first wedge-shapedprotuberances are circumferentially spaced-apart from one another anddisposed radially outwardly from the flanges.
 9. A centrifugal pumpaccording to claim 7, wherein the casing arrangement has definedthereon, on axially opposite sides of and in spaced relation to theimpeller, a plurality of second wedge-shaped protuberances; and thespaces between the impeller and the second wedge-shaped protuberancesdefine the second portion.
 10. A centrifugal pump according to claim 9,wherein the second wedge-shaped protuberances are formed on a pair ofannular inserts fitted in hollows formed, respectively, on the front andcentral casing.
 11. A centrifugal pump according to claim 2, wherein therotor further comprises a drive member and a shaft coupling the rotor tothe drive member for rotation therewith, and wherein the magnetarrangement is adapted to drive said rotation of said rotor by causingrotation of said drive member.
 12. A centrifugal pump according to claim11, wherein the rotor and casing arrangement are shaped such that athird portion of the space between the rotor and the casing arrangement,in use, measured radially, undulates in magnitude around the drivemember for stabilizing the rotor against radial movement.
 13. Acentrifugal pump according to claim 12, wherein measured radially, inthe direction of rotation of the rotor, in each undulation in the thirdportion the space between the rotor and the casing arrangement graduallydecreases and then quickly increases.
 14. A centrifugal pump accordingto claim 13, wherein the drive member has projecting in an axialdirection therefrom a circular flange, arranged coaxial with the axis;the casing arrangement has defined therein a circular channel in whichthe flange rotates in use; the channel has defined therein a pluralityof first wedge-shaped protuberances; and the space between the flange,channel and first wedge-shaped protuberances define the third portion.15. A centrifugal pump according to claim 14, wherein the firstwedge-shaped protuberances are circumferentially spaced-apart from oneanother and disposed radially outwardly from the flanges.
 16. Acentrifugal pump according to claim 2, wherein said adaptation of therotor and casing arrangement, such that said liquid supports said rotorin use for rotation substantially about said axis in spaced relation tosaid hollow casing arrangement, comprises: a first wedge device whicharrests radial translation of the rotor in use; and a second wedgedevice which arrests axial translation of the rotor in use.
 17. Acentrifugal pump according to claim 1, further comprising: a first wedgedevice which arrests radial translation of the rotor in use; and asecond wedge device which arrests axial translation of the rotor in use.18. A centrifugal pump according to claim 3, further comprising: a firstwedge device which arrests radial translation of the rotor in use; and asecond wedge device which arrests axial translation of the rotor in use.19. A centrifugal pump according to claim 1, wherein the shaft haspositioned thereon at least one wing for arresting liquid flow from theimpeller towards the drive member in use.
 20. A centrifugal pumpaccording to claim 19, wherein said at least one wing is a spiral wing.21. A centrifugal pump according to claim 19, further comprising aconduit providing for fluid communication between a portion of theinterior in which the drive member is positioned and the intake port.22. A centrifugal pump according to claim 1, wherein the drive membercomprises: a rotor plate having a rim; and a non-magnetic electricalconductor secured to said rim, the conductor having a surface coated inan insulator, the casing arrangement includes a non-magnetic electricalinsulating barrier between the conductor and the magnet arrangement, andthe magnet arrangement comprises two sets of permanent magnetssurrounding said conductor and rotatable in use such that, upon saidrotation, said rotating magnetic field is generated between the two setsof magnets to intersect the conductor.
 23. A centrifugal pump accordingto claim 22, wherein the conductor is an annular disc; and each of thetwo sets of permanent magnets includes an even number of permanentmagnets arranged in an arc and attached to a yoke, the yokes of the twosets being connected together and the two sets of permanent magnetsbeing axially spaced from one another.
 24. A centrifugal pump accordingto claim 22, wherein the conductor is a hollow cylinder; and each of thetwo sets of permanent magnets includes an even number of permanentmagnets arranged in an arc and attached to a cylindrical yoke, the yokesof the two sets being connected together and the two sets of permanentmagnets being radially spaced from one another.
 25. In combination, acentrifugal pump according to claim 2; and a motor, said motor beingcoupled to said magnet arrangement and, in use, driving said magnetarrangement to create said rotating magnetic field.